The most advanced activity tracker known to man, <b>Jawbone</b>&#39;s <b>UP3</b> is packed with state-of-the-art sensors that give you the full picture of your health. Heart Health Sensor measures resting heart rate - a leading indicator of your overall health and fitness level. Workouts are automatically recognised and logged. You&#39;ll gain an in-depth understanding of your sleep. All this, in an impossibly small design and a full week of battery life.